Because most production bugs are infrequent (otherwise they would be noticed by testing). They have to be logged and fixed, but not allowed to move the system into inconsistent state. Restart first, fix later.
Are they? The bug discussed in this comment was extremely deterministic. There's a difference between infrequent in the sense that, across lots of users and lots of requests it happens rarely, and infrequent in the sense that, for one particular use, it only triggers sometimes.
Also, the bug discussed in this article wasn't causing crashes. What would you propose be crashed and restarted in this case?
Also, the bug discussed in this article wasn't causing crashes. What would you propose be crashed and restarted in this case?